The femoral intercondylar notch is the horseshoe-shaped depression between the medial and lateral femoral condyles on the posterior and inferior surface of the distal femur. The ACL originates from the inner surface of the lateral condyle wall in the notch, and the PCL from the inner surface of the medial condyle wall. The roof of the notch (intercondylar roof or over-the-top position) is an important surgical landmark. Notch width and height are measured on MRI and are correlated with ACL injury risk.
A narrow intercondylar notch (notch width index less than 0.2) is an independent risk factor for non-contact ACL injury, particularly in females who have narrower notches on average. Notch stenosis after previous ACL surgery or in ACL-injured knees can cause graft impingement during extension. Notchplasty (enlargement of the notch) is performed during ACL reconstruction when impingement is anticipated. The notch dimensions also determine the available space for PCL and posterolateral corner reconstruction tunnels.
A narrow or stenotic intercondylar notch contacts the ACL graft during terminal extension if tunnel placement or notch size is not optimised, causing graft abrasion and failure; arthroscopic notchplasty resects the lateral notch wall to create adequate graft clearance in extension.
A narrow intercondylar notch width index below 0.2 is associated with increased contact stress on the ACL during pivoting activities, contributing to the higher ACL injury rate in female athletes who on average have narrower notches than males, forming the anatomical basis for preventive training programme development.
